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    SubjectRe: [PATCH v8 15/19] locking/rwsem: Adaptive disabling of reader optimistic spinning
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    On 6/4/19 1:38 PM, Peter Zijlstra wrote:
    > On Tue, Jun 04, 2019 at 01:30:00PM -0400, Waiman Long wrote:
    >>> That's somewhat inconsistent wrt the type. I'll make it unsigned long,
    >>> as that is what makes most sense, given there's a pointer inside.
    >> Thank for spotting that, I will fix it.
    > I fixed a whole bunch of them; please find the modified patches here:
    >
    > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=locking/core

    Thanks for reviewing the patches.

    So how do you think about the overall state of this patchset? Do you
    think it is mature enough to go into 5.3?

    Or if you want more time to think about solving the RT thread issue, we
    can merge just patches 1-16 and play with the last threes for some more
    time. I am fine with that too as improving RT tasks is not my main
    focus. I like patch 16 as it led me to discover the rwsem reader wakeup
    bug as I hit the negative dentry count WARN_ON message in my testing.

    I worked on this owner merging patch mainly to alleviate the need to use
    cmpxchg for reader lock. cmpxchg_double() is certainly one possible
    solution though it won't work on older CPUs. We can have a config option
    to use cmpxchg_double as it may increase the size of other structures
    that embedded rwsem and impose additional alignment constraint.

    Cheers,
    Longman


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